The star of an Oscar-winning film about dolphin hunting in Japan delivered a petition to the country's US embassy calling for an end to the practice.

Ric O'Barry, 70 – who appeared in The Cove and trained dolphins for 1960s TV show Flipper – was flanked by police and dozens of supporters carrying banners. The petition was signed by 1.7 million people from 151 countries.

O'Barry had hoped to deliver it to the Japanese fisheries agency but cancelled the plan after threats from a nationalist group with a history of violence. The Cove, which won this year's Oscar for best documentary, shows fishermen from the town of Taiji who scare dolphins into a cove before killing them slowly by piercing them repeatedly.

O'Barry said: "I'm not losing hope. Our voice is being heard in Taiji."

The annual hunt in the town began on Wednesday, but boats came back empty. The government allows the hunting of around 20,000 dolphins a year and argues that killing them is no different from breeding cows and pigs for slaughter. Most Japanese have never eaten dolphin meat and, even in Taiji, it is not consumed regularly.